This application claims the priority of German application 197 34 425.9, filed in Germany on Aug. 8, 1997, the disclosure of which is expressly incorporated by reference herein.
The present invention relates to a step bearing for a shaft of a spinning rotor, which in use is loaded with an axial force. A freely rotatable supporting ball is disposed against a thrust bearing, against which supporting ball the shaft is supported by means of a front end supporting surface. The supporting ball is housed in a take-up receptacle for lubricating grease fed to the supporting surface.
U.S. Pat. No. 4,618,273 discloses a step bearing of the above mentioned type. Here the take-up receptacle for the lubricating grease is a part of a larger housing, which also contains a collecting container for used lubricating grease. When the available lubricating grease is used up, fresh lubricating grease can be applied to the take-up receptacle with the aid of a correspondingly formed lubricating grease injector. The take-up receptacle is not disassembled for this purpose. In a variation of the known step bearing, the collecting container can be disassembled for cleaning purposes. Subsequent lubrication in the case of the known step bearing is labor intensive and requires special equipment.
It is an object of the present invention to design a step bearing of the above mentioned type so that subsequent lubrication is simplified.
This object has been achieved in accordance with the present invention in that the take-up receptacle for lubricating grease is arranged in a cartridge, which is clamped fixedly by means of a cylindrical outer surface in a corresponding hollow cylindrical take-up surface of a stationary supporting part, whereby the cartridge further comprises the freely rotatable supporting ball for supporting the end of the shaft, as well as the thrust bearing which is screwed onto the cartridge.
It is thus possible, after the lubricating grease has been used up, to exchange the cartridge for a cartridge with fresh lubricating grease in a simple way. The cartridge is not dismantled when it is disassembled, rather the supporting ball remains in the cartridge. A new cartridge with the necessary supply of lubricating grease and also comprising a supporting ball is assembled.
Although the cartridge can be designed as a disposable part, it is often worth using at least the screw-on thrust bearing and possibly also the unworn supporting ball again. For this reason, the used cartridge can be accordingly prepared for reuse outside of the open-end spinning aggregate.
For the purpose of the present invention, the cylindrical outer surface has a diameter of approximately 14 mm. It is thus possible in the case of known machines to replace an aerostatic axial bearing for the shaft of the spinning rotor with a step bearing comprising the cartridge without any difficulties, whereby namely a bearing tube arranged to the aerostatic axial bearing is taken out of the hollow cylindrical take-up surface after the clamp has been released and replaced by insertion of the cartridge. This process for replacing an aerostatic axial bearing by means of the step bearing of the present invention is in particular advantageous for retrofitting and modernizing older open-end spinning machines. A replaceable, aerostatic axial bearing of this type is disclosed in U.S. Pat. No. 5,450,718.